A standard disk drive includes space for storing data available to the user and a fixed amount of space that is kept in reserve for storing data unavailable to the user. After the manufacturer writes a servo pattern on the disk or disks in a disk drive, the manufacturer fixes the amount of space that is available to the user and the amount of space that is unavailable to the user. Servo writing the disks in the disk drive provides positional information for finding a particular track or group of tracks. The manufacturer then designates that a certain number of tracks will be set aside for the reserve area. The manufacturer then writes certain critical information to the tracks in the reserve area. The critical information is typically required to operate the disk drive and is used by the operating system or hardware in the operation of the drive. In the past, no one beyond the original disk drive manufacturer could access the reserve area. The reserve area was simply protected. The reserve area was even off limits to a computer system manufacturer that integrated the disk drive into a computer system. In the past, a computer system manufacturer could not modify or change the size of the reserve area. No such command or set of commands would allow anyone beyond the manufacturer of the disk drive to change anything with respect to the reserve area as set up by the manufacturer.
The disk drive is basically a nonvolatile source of memory. In other words, after the power is removed from the disk drive, the disk drive maintains the information stored thereon indefinitely. The storage capacity of disk drives has risen dramatically over the past few years and the cost of that storage capacity, commonly priced as the cost per megabyte of disk drive storage has dropped dramatically. The result is that now disk drives have become an attractive alternative to nonvolatile storage in a ceramic chips or integrated circuits, since the cost of storage on a disk drive is much less expensive and since disk drives are already included in most computer systems as one rarely sees a computer system without a disk drive.
The only option at present for computer system manufacturers seeking to write information to a disk rather than to a ROM, is to write to an area of the disk to which the user has access. This option is simply unacceptable, since critical information written to this area of the disk could be overwritten at anytime. Overwriting would be the same as erasing the critical data written to the disk. Overwriting or erasure would have devastating effects. Basic instructions necessary to operate the computer system would be erased leaving the user with useless hardware. In addition, viruses downloaded from other sources such as the Internet, could attack critical information written to an area of the disk to which users have access. Although writing critical information to a disk is currently an attractive alternative from a perspective of cost, computer system manufacturers will not write such information to a disk since one could potentially overwrite any critical information written on the disk. There is no current way to modify the disk drive so that a computer manufacturer will be assured that information written to a disk will not be overwritten or erased. There is a need to reduce the cost of computer systems. There is also a need to provide safe and low cost nonvolatile storage of system manufacturer related critical information used to operate computer systems.